1. Field of the Invention
This invention relates to a step-by-step motor able to carry out up-and-down motion, particularly to one able to manually adjust a top rod to actuate the headlamp of an automobile to move upward or downward to a proper level by inserting an adjustment tool into a through hole of a cover body from the exterior of a cover body.
2. Description of the Prior Art
Generally, the headlamp of an automobile is provided with a step-by-step motor for adjusting the level of the headlamp. A conventional step-by-step motor 1, as shown in FIGS. 1, 2 and 3, includes a housing 10, a driven worm gear 11, a transmitting worm gear 12, a top rod 13, an interacting member 14, a circuit board 15, a cover body 16, a serrated plate 17 and an adjusting block 18 combined together.
The housing 10 is provided inside with an accommodating chamber 100 having its interior formed with a recessed chamber 101 having a central insert hole 102 passing through the topside of the housing 10. The housing 10 further has its peripheral wall bored with a plurality of engage slots 103 spaced apart.
The driven worm gear 11 to be received in the accommodating chamber 100 of the housing 10 is provided with a connecting block 110 at the upper side and bored with a central insert hole 111 formed with female threads 112.
The transmitting worm gear 12 to be assembled at one side of the driven worm gear 11 has one side disposed with a driven worm 120 engaged with the driven worm gear 11 and the other side fixed with a support shaft 121.
The top rod 13 to be inserted through both the insert hole 111 of the driven worm gear 11 and the insert hole 102 of the housing 10 has its upper section provided with male threads 130 and its intermediate outer wall secured with an annular blocking plate 131. Further, the top rod 13 has its outer wall bored with an annular recess 132 near the lower end and has its lower section formed with an insert rod 133.
The interacting member 14 is to be fitted around the top rod 13 and inserted through the insert hole 111 and 102 of the driven worm gear 11 and the housing 10. The interacting member 14 has its outer circumferential wall provided with male threads 140 and its lower side provided with an interacting block 141 with an engage notch 142, and is further bored in the interior with a central insert hole 143 having a plurality of engage blocks 144 fixed near the bottom to be engaged with the annular recess 132 of the top rod 13.
The circuit board 15 to be received in the accommodating chamber 100 of the housing 10 is assembled thereon with a transmitting motor 150 having a transmitting worm 151 engaged with the transmitting worm gear 12, and a position-limiting switch 152 provided with a cross bar 153 to be engaged in the engage notch 142 of the interacting member 14.
The cover body 16 to be covered on the bottom of the housing 10 has its peripheral outer wall fixed thereon with a plurality of engage projections 160 spaced apart to be respectively engaged and positioned in the engage slots 103 of the housing 10, and its bottom side formed with a recessed chamber 161, which has its peripheral wall cut with plural notches 162 spaced apart and its interior fixed with a projecting post 163 with a central insert hole 164.
The serrated disc 17 is to be positioned in the recessed chamber 161 at the lower side of the cover body 16 to resist against the lower side of the projecting post 163 of the cover body 16. The serrated disc 17 has one side disposed with a plurality of engage notches 170 and its center bored with an insert hole 171 aligned to the insert hole 164 of the projecting post 163 of the cover body 16.
The adjusting block 18 to be positioned under the serrated disc 17 is secured in the center with a projecting post 180 to be inserted through the insert hole 171 of the serrated plate 17 and positioned in the insert hole 164 of the cover body 16. The projecting post 180 of the adjusting block 18 is bored with a central insert hole 181 for the insert rod 133 of the top rod 13 to be inserted therein. Further, the adjusting block 18 has its underside cut with a slit 182 for an adjustment tool 19 to be inserted and turned therein, thus finishing assembly of the conventional step-by-step motor 1.
However, the adjustment structure of the conventional step-by-step motor 1 for manually adjusting the top rod 13 to move upward or downward is provided under the cover body 16, and the serrated disc 17 and the adjusting block 18 are positioned at the exterior of the cover body 16 without being covered by the cover body 16. Under the circumstances, the serrated disc 17 and the adjusting block 18 are likely to fall off the cover body 16 and easy to be damaged, rendering the top rod 13 impossible to be manually adjusted to move upward or downward. In addition, in case the transmitting motor 150 of the step-by-step motor 1 cannot be started to operate, it is impossible to carry out adjustment manually.